bubble_chart Overview

Meningitis caused by craniocerebral injury is commonly seen in patients with skull base fractures accompanied by cerebrospinal fluid fistula, or due to penetrating open head injuries. However, in the latter case, if treated properly early on, the chance of developing meningitis is much lower than expected. Pyogenic bacteria can enter the subarachnoid space not only through open wounds but also via the bloodstream, respiratory tract, paranasal sinuses, middle ear, mastoid region, or even the sella turcica. Common pathogens include staphylococci, streptococci, Escherichia coli, and Pseudomonas aeruginosa. However, purulent meningitis introduced through the frontal or ethmoid sinuses into the cranial cavity is more frequently caused by pneumococci.

bubble_chart Clinical Manifestations

After the onset of illness, patients in the acute phase often experience headache, nausea, vomiting, general fear of cold, rapid pulse, elevated body temperature, positive meningeal irritation signs, and neck stiffness. However, a small number of patients with meningitis may have an insidious onset, such as recurrent intracranial infections caused by cerebrospinal fluid fistula disease, which may show no obvious discomfort within 1–2 days after infection. Advanced-stage meningitis caused by penetrating craniocerebral injuries often results from deep brain infections invading the ventricular system or abscess rupture. Once infection occurs, the inflammatory response in the subarachnoid space due to bacterial toxins will lead to cerebral edema, increased intracranial pressure, and impaired cerebral blood flow. Without timely and appropriate treatment, severe complications and sequelae often arise, such as brain abscess, hydrocephalus, brain swelling, subdural empyema, and cerebrovascular damage, with a mortality rate as high as 18.6%.

bubble_chart Diagnosis

The diagnosis of bacterial meningitis primarily relies on laboratory tests. The cerebrospinal fluid appears turbid, sometimes even purulent, with significantly elevated cells and protein levels, decreased sugar content, and occasionally positive bacterial cultures. Peripheral blood tests also show increased total white blood cell counts and neutrophilia. Generally, CT scans often reveal no abnormalities, but in severe cases, high-density shadows may be observed in the basal cisterns and the interhemispheric fissure, along with increased density of the choroid plexus. When encephalitis complicates the condition, localized or diffuse low-density areas appear in the brain parenchyma, and the ventricles symmetrically shrink. During contrast-enhanced scans, the leptomeninges and cerebral cortex may exhibit thin linear or gyriform enhancement. CT is particularly useful for diagnosing complications such as brain abscesses, hydrocephalus, subdural empyema, or ventriculitis. Therefore, for patients suspected of having meningitis, early lumbar puncture for cerebrospinal fluid analysis is recommended to confirm the diagnosis promptly and initiate timely treatment. For late-stage complications, CT scans should be performed to guide further management. Routine CT scanning before lumbar puncture is not advisable.

bubble_chart Treatment Measures

The treatment of bacterial meningitis should be initiated as early as possible with potent antibiotics that can penetrate the blood-brain barrier, based on timely identification of the causative pathogen. The dose must be sufficient, and the treatment course must be long enough. Commonly used regimens include penicillin 400×10⁴

units administered intravenously twice daily; erythromycin or chloramphenicol 1–1.5 g intravenously once daily; and sodium sulfadiazine 3 g intravenously twice daily. Currently, 5% sodium bicarbonate is administered at 3–5 ml/kg to alkalinize the urine. Additionally, the principles and methods for selecting potent drugs based on different bacterial species have been described earlier.

While systemic medication is being administered, lumbar puncture should also be performed daily or every other day. This not only drains inflammatory cerebrospinal fluid but also facilitates intrathecal drug administration. Typically, gentamicin 20,000–40,000 units diluted in 10–15 ml of normal saline is slowly injected intrathecally once daily or every other day. However, care must be taken to avoid excessively high concentrations to prevent irritation and adhesions. Furthermore, eliminating the disease cause is a crucial step that cannot be overlooked. If conditions such as cerebrospinal fluid fistula, intracranial foreign bodies or infections, epidural or subdural empyema, and/or brain abscess are present, corresponding surgical interventions should be planned accordingly.